Reflection-type liquid crystal display and method for manufacturing the same

ABSTRACT

A reflection-type liquid crystal display according to the invention includes two glass substrates, a transparent electrode provided on one glass substrate, an insulator film which is provided on another glass substrate and on which an uneven structure is formed, a reflecting electrode provided on the insulator film, and a liquid crystal layer sandwiched between a side of the transparent electrode and a side of the reflecting electrode. The insulator film includes a first insulating layer in which a large number of depressions isolated as surrounded by protrusions are irregularly arranged and a second insulating layer covering the insulating layer entirely. The protrusions are all connected in a network, so that if some of these protrusions have weaker adherence with an underlying layer, they can be supported by the surrounding protrusions.

This is a divisional of application Ser. No. 10/831,118, filed Apr. 26,2004 now U.S. Pat. No. 7,215,394, which is a divisional of applicationSer. No. 09/765,366, filed Jan. 22, 2001, now U.S. Pat. No. 6,747,718,issued Jun. 8, 2004, which claims priority from Japanese PatentApplication No. 2000-013216, filed Jan. 21, 2000, the entire disclosureof which applications are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a reflection-type liquid crystal display havinga reflecting plate for reflecting out a light transmitted through aliquid crystal layer from an outside and a method for manufacturing asame.

The present application claims priority of Japanese Patent ApplicationNo. 2000-013216 filed on Jan. 21, 2000, which is hereby incorporated byreference.

2. Description of the Related Art

Reflection-type liquid crystal displays have been used mainly in aportable terminal because they can be made thinner, less powerconsuming, and lighter in weight than transmission-type ones.Specifically, a reflecting plate in the reflection-type liquid crystaldisplay reflects an incident light transmitted from the outside, and itis therefore available as a light source for display, thus eliminating anecessity of a back-light.

A recent reflection-type liquid crystal display includes basically aliquid crystal of, for example, a TN (Twisted Nematic)-type, a singlepolarizing plate-type, a STN (Super Twisted Nematic)-type, a GH (guesthost)-type, or a PDLC (Polymer Dispersion)-type, a Cholesteric-type, oralike, a switching element for driving the liquid crystal, and areflecting plate provided inside or outside a liquid crystal cell. Sucha typical reflection-type liquid crystal display employs an activematrix scheme which realizes high definition and high picture quality byusing a TFT (TFT) or metal/insulator film/metal-structured diode (MIM)as the switching element and also has the reflecting plate attachedthereto.

The following will describe a conventional liquid crystal display of thesingle polarizing plate-type with reference to FIG. 19.

An opposed-side substrate 1 includes a polarizing plate 2, aphase-difference plate 3, a glass substrate 4, a color filter 5, and atransparent electrode 6. A lower side substrate 7 includes, on the otherhand, a glass substrate 8, a reverse stagger-structured TFT 9 formed asa switching element on the glass substrate 8, a protrusion shape 10 madeup of a first insulating layer which provides an unevenly-structuredbase, a polyimide film 11 formed thereon as a second insulating layer,and a reflecting electrode 13 which is connected to a source electrode12 of the TFT 9 and also which functions as a reflecting plate-and-pixelelectrode.

Between the opposed-side substrate 1 and the lower side substrate 7 islocated a liquid crystal layer 14.

A reflected light 16 is utilized for display. The reflected light 16 isgiven by an incident light 15 from outside when it passes through thepolarizing plate 2, the phase-difference plate 3, the glass substrate 4,the color filter 5, the transparent electrode 6, and the liquid crystallayer 14 and then is reflected by the reflecting electrode 13.

This reflection-type liquid crystal display needs to have such displayperformance that it would give bright and white display when the liquidcrystal is in a light-transmitting state. To achieve this displayperformance, the incident light 15 transmitted in various orientationsneeds to be efficiently emitted to the outside. To do so, an unevenstructure can be formed on the polyimide film 11 to thereby provide thereflecting electrode 13 located thereon with a light-scatteringfunction. Therefore, the display performance of the reflection-typeliquid crystal display largely depends on how to control the unevenstructure of the reflecting electrode 13.

The following will describe a conventional method for manufacturing areflecting electrode used in the conventional reflection-type liquidcrystal display with reference to FIG. 20A and FIG. 21J.

In steps for manufacturing a TFT, first a gate electrode 21 is formed ona glass substrate 20 (FIG. 20A). Subsequently, a gate insulator film 22,a semiconductor layer 23, and a doping layer 24 are formed (FIG. 20B).Subsequently, an island 25 of the semiconductor layer 23 and the dopinglayer 24 is formed (FIG. 20C), thereby forming a source electrode 26 anda drain electrode 27 (FIG. 20D). Next, a reflecting electrode 34 isformed.

In steps for manufacturing the reflecting electrode, first an organicinsulator film 28 is formed which has photosensitivity (FIG. 20E).Subsequently, protrusions 29 are formed by photolithography in a regionfor forming the reflecting electrode (FIG. 20F) and melted into a smoothprotrusion shape 30 (FIG. 21G). Subsequently, the smooth protrusionshape 30 is covered with an organic insulator film 31 to form a furthersmoother uneven surface 32 (FIG. 21H). Subsequently, to electricallyconnect the reflecting electrode to the source electrode of the TFT, acontact portion 33 is formed (FIG. 21I), to then form a reflectingelectrode 34 (FIG. 21J). This method for manufacturing reflectingelectrodes is disclosed for example in Japanese Examined PatentApplication No. Sho 61-6390 and in Proceedings of the SID (Tohru Koizumiand Tatsuo Uchida, Vol. 29, p. 157, 1988).

FIG. 22 is a plan view of a pattern of the protrusions 29 in the FIG.20F. The following will describe the process with reference to FIG. 22F.

Protrusions 29 are not in contact with each other, that is mutuallyisolated. The protrusions 29 are each extremely small, measuring 1-20 μmin diameter and 0.5-5.0 .mu. m in height. Therefore, during a subsequentsubstrate washing process, a heating process, or a film forming process,adherence between the protrusions 29 and underlying layer maydeteriorate, thus causing the protrusions 29 to problematically flakeoff.

With this, therefore, a desired uneven structure cannot be formed in areflecting electrode region, so that a desired optical property cannotbe obtained for the reflecting electrode. That is, such the reflectionelectrode, if used in the reflection-type liquid crystal display, wouldgive dark display or irregularities in brightness.

To prevent flake-off of the protrusions, also, it may be suggested thata coupling material be applied under the protrusions 29 to improveadherence. Under and below the protrusions 29, however, the TFT, thewiring lines, and a like are arranged, so that they may be adverselyinfluenced by the coupling material, thus deteriorating reliability ofthe switching element. Therefore, the coupling material should not beused.

SUMMARY OF THE INVENTION

In view of the above, it is an object of the invention to provide areflection-type liquid crystal display which prevents flake-off ofprotrusions which provide a base for the uneven structure of areflecting electrode to thereby achieve high brightness and highdefinition display performance, and a method for manufacturing same.

According to a first aspect of the present invention, there is provideda reflection-type liquid crystal display including:

a transparent first substrate;

a transparent electrode provided on the transparent first substrate;

a second substrate;

an insulator film which is provided on the second substrate and also ona surface of which is formed an uneven structure;

a reflecting electrode which is provided on the insulator film in such ashape as reflecting the uneven structure; and

a liquid crystal layer sandwiched by a side of the transparent electrodeformed on the first substrate and a side of the reflecting electrodeprovided on the second substrate;

wherein the insulator film includes a first insulating layer in which alarge number of depressions are irregularly arranged which are isolatedas surrounded by protrusions and a second insulating layer which coversthe first insulating layer entirely.

In the foregoing-first aspect, the depressions refer to portions wherethere is essentially no film thickness present and so may be calledapertures, through-holes or a like instead.

Protrusions on the first insulating layer according to a prior art arenot in contact with each other, that is, are isolated. Therefore, ifsome of all the protrusions have weaker adherence with the underlyinglayer, they easily flake off. The protrusions on the first insulatinglayer according to the first aspect are all connected in a network.Therefore, even if some of those protrusions have a weaker adherencewith an underlying layer, they may be supported by surroundingprotrusions. With this, the protrusions can be prevented from flakingoff.

In other words, the protrusions on the first insulating layer accordingto the first aspect are formed by an irregular arrangement of isolateddepression patterns. Since the protrusions on the first insulating layeraccording to the prior art are formed by an irregular arrangement ofisolated columnar protrusions, they easily flake off during subsequentmanufacturing processes. With the first aspect the isolated depressionpatterns are irregularly arranged to thereby increase a contact areabetween the protrusions and the underlying layer, so that theprotrusions do not easily flake off during subsequent manufacturingprocesses.

Also, those protrusions may be formed by an irregular arrangement ofstripe-shaped protrusion patterns. If, in this case, the protrusions areformed by an irregular arrangement of stripe-shaped protrusion patterns,they have a larger contact area with the underlying layer than thecolumnar protrusion patterns according to the prior art, thus improvingadherence.

Also, in the above-mentioned uneven structure, irregular uneven shapesmay be repeatedly formed in an entire region of a reflecting electrodein units of one pixel (picture element) or more. With this, it ispossible to suppress interference of reflecting properties, so that thereflection-type liquid crystal display employing this reflectingelectrode is free of wavelength dependency without deterioration incolor properties, thus providing bright and high-definition displayperformance.

Also, the above-mentioned protrusions may be melted into a smoothsectional shape. Next, these protrusions are covered by the secondinsulating layer formed subsequently, to obtain the uneven structure, sothat the reflecting electrode formed thereon has good optical reflectingproperties, thus permitting the reflection-type liquid crystal displayhaving this reflecting electrode in the liquid crystal cell to givebrighter display.

Also, the above-mentioned first or second insulating layer can act alsoas a protection film for a switching element, to prevent it from beingcontaminated from outside, thus achieving stable switching operations.

Also, at least one of the first and second insulating layers can coverwiring lines (at least one of drain and gate wiring lines), to reduce aparasitic capacitance due to the wiring lines and the reflectingelectrode, thus suppressing occurrence of cross-talk or a like in thereflection-type liquid crystal display.

Also, at least one of the first and second insulating layers hasphoto-absorbancy to thus absorb an incident light from between mutualreflecting electrodes. With this, the incident light can be preventedfrom being applied to the switching element to thereby good switchingproperties, thus resulting in the reflection-type liquid crystal displayhaving high contrast and high brightness display properties.

Also, at least one of the first and second insulating layers may have acontact hole made therein for electrically interconnecting thereflecting electrode and underlying switching element. In this case, thereflecting electrode can be provided at a top of a pixel and so can beincreased in area to achieve a higher numerical aperture, thusimplementing the reflection-type liquid crystal display having brighterdisplay performance.

Also, by forming the protrusions of an organic or inorganic materialhaving photosensitivity, patterning step for forming the protrusions canbe shortened. Also, by forming the second insulating layer of an organicor inorganic material having photosensitivity, the patterning step forforming contact pattern can be shortened to thereby simplify processrequired, thus reducing cost for manufacturing the reflection-typeliquid crystal display.

According to a second aspect of the present invention, there is provideda reflection-type liquid crystal display manufacturing method forforming an uneven structure in the reflection-type liquid crystaldisplay according to the first aspect, the manufacturing methodincluding steps of:

forming a first insulating layer of an organic or inorganic insulatingmaterial having photosensitivity;

forming an uneven-element pattern on the first insulating layer byphoto-exposure;

etch-developing on the first insulating layer;

melting by heat treatment the first insulating layer thusetch-developed, to thereby smooth an uneven structure; and

forming a second insulating layer on the first insulating layer thusmelted.

With the above second aspect, it is possible to omit the resistapplying, flaking, and etching steps of the resist process in patterningof the depression-protrusion portion (step), thus simplifying processand reducing costs of the reflection-type liquid crystal display. Inaddition, a smooth and continuous uneven structure can be manufactured,thus implementing a reflecting electrode which has a uniform and unevensurface free of protrusion flake-off.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, advantages and features of the presentinvention will be more apparent from the following description taken inconjunction with the accompanying drawings in which:

FIG. 1 is a cross-sectional view showing a reflection-type liquidcrystal display according to a first embodiment of the presentinvention;

FIG. 2A and FIG. 2B are plan views showing one pixel area of a firstinsulating layer in the reflection-type liquid crystal display accordingto a first embodiment of the present invention, FIG. 2A showing a firstmode of the first embodiment and FIG. 2B showing a second mode of thefirst embodiment;

FIG. 3A and FIG. 3B are explanatory illustrations showing areflection-type liquid crystal display according to a second embodimentof the present invention, FIG. 3A showing a first mode of the secondembodiment and FIG. 3B showing a second mode of the second embodiment;

FIG. 4A is a cross-sectional view showing a reflection-type liquidcrystal display according to a third embodiment of the presentinvention.

FIG. 4B is a cross-sectional view showing a reflection-type liquidcrystal display according to a fourth embodiment of the presentinvention.

FIG. 5A through FIG. 5C are cross-sectional views showing areflection-type liquid crystal display according to a fifth embodimentof the present invention, FIG. 5A showing a comparison example, FIG. 5Bshowing a first mode of the fifth embodiment, and FIG. 5C showing asecond mode of the fifth embodiment;

FIG. 6 is a cross-sectional view showing a reflection-type liquidcrystal display according to a sixth embodiment of the presentinvention;

FIG. 7AB through FIG. 7G are cross-sectional views showing a method formanufacturing a reflection-type liquid crystal display according to afirst embodiment of the present invention, steps being performed inorder of FIG. 7AB through FIG. 7G;

FIG. 8H through FIG. 8L are cross-sectional views showing the method formanufacturing showing continued process steps of the reflection-typeliquid crystal display according to the first embodiment of the presentinvention, the steps being performed in order of FIG. 8H through FIG.8L;

FIG. 9AB through FIG. 9H are cross-sectional views showing areflection-type liquid crystal display according to a first example ofthe present invention, steps being performed in order of FIG. 9ABthrough FIG. 9H;

FIG. 10I through FIG. 10LM are cross-sectional views showing continuedsteps of the reflection-type liquid crystal display according to thefirst example of the present invention, the steps being performed inorder of FIG. 10I through FIG. 10LM;

FIG. 11 is a plan view showing one protrusion pattern according to thefirst example of the present invention;

FIG. 12 is a plan view showing another protrusion pattern according tothe first example of the present invention;

FIG. 13AB through FIG. 13G are cross-sectional views showing a thereflection-type liquid crystal display according to a second example ofthe present invention, steps being performed in order of FIG. 13ABthrough FIG. 13G;

FIG. 14H through FIG. 14KL are cross-sectional views showing continuedsteps of the liquid crystal display according to the second example ofthe present invention, the steps being performed in order of FIG. 14Hthrough FIG. 14KL;

FIG. 15AB through FIG. 15G are cross-sectional views showing areflection-type liquid crystal display according to a third example ofthe present invention, steps being performed in order of FIG. 15ABthrough FIG. 15G;

FIG. 16H through FIG. 16L are cross-sectional views showing continuedsteps of the reflection-type liquid crystal display according to thethird example of the present invention, the steps being performed inorder of FIG. 16H through FIG. 16L;

FIG. 17 is a plan view showing one protrusion pattern according to afifth example;

FIG. 18 is a plan view showing another protrusion pattern according tothe fifth example;

FIG. 19 is a cross-sectional view showing a conventional reflection-typeliquid crystal display;

FIG. 20A through FIG. 20F are cross-sectional views showing a method formanufacturing a conventional reflection-type liquid crystal display,steps being performed in order of FIG. 20A through FIG. 20F;

FIG. 21G through FIG. 21J are cross-sectional views showing continuedsteps of the method for manufacturing a conventional reflection-typeliquid crystal display, the steps being performed in order of FIG. 21 Gthrough FIG. 21J; and

FIG. 22 is a plan view showing a protrusion pattern of a conventionalreflection-type liquid crystal display.

DETAILED DESCRIPTION OF THE INVENTION

Best modes of carrying out the present invention will be described infurther detail using various embodiments with reference to theaccompanying drawings.

First Embodiment

The following will describe a reflection-type liquid crystal displayaccording to a first embodiment of the present invention with referenceto FIG. 1.

The reflection-type liquid crystal display of the first embodiment, asshown in FIG. 1, includes a glass substrate 581 as a transparent firstsubstrate, a transparent electrode 60 provided on the glass substrate581, a glass substrate 582 as a second substrate, an insulator film 44which is provided on the glass substrate 582 and on which an unevenstructure 50 is formed, a reflecting electrode 51 provided on theinsulator film 44 in such a shape as reflecting the uneven structure 50,and a liquid crystal layer 61 sandwiched between the transparentelectrode 60 of the glass substrate 581 and the reflecting electrode 51of the glass substrate 582. The insulator film 44 in this configurationincludes a first insulating layer 45 in which a large number ofdepressions 46 each isolated as surrounded by a protrusion 47 areirregularly arranged and a second insulating layer 49 covering the firstinsulating layer 45 entirely. The protrusions 47 are as a wholeconnected in a network. Therefore, if some of these protrusions 47 haveweaker adherence with the underlying layer, they are supported by thesurrounding protrusions 47. With this, they can be prevented fromflaking off.

In the first embodiment, between a mutually opposing lower sidesubstrate 7 and an opposed-side substrate 1 is provided the liquidcrystal layer 61. The lower side substrate 7 includes a reversestagger-structured TFT 40 formed as a switching element on the glasssubstrate 582, an insulator film 44 having the uneven structure 50thereon, and the reflecting electrode 51 made of high reflectionefficiency metal which is formed so as to cover the insulator film 44.

The TFT 40 includes a gate electrode, a gate insulator film, asemiconductor film, a source electrode, and a drain electrode which areformed by forming a metal layer 41, an insulating layer 42, asemiconductor layer 43, or a like and then performing photolithographyand etching processes thereon. Also, the TFT 40 has thereon the firstinsulating layer 45 made of an organic or inorganic insulating layer.The first insulating layer 45 has thereon the isolated depressions 46and the continuous protrusions 47. Those depressions 46 and protrusions47 are disposed irregularly. The second insulating layer 49 covers thedepressions 46 and the protrusions 47, thereby having the unevenstructure formed thereon. By forming high-reflectance metal on theuneven structure 50, the reflecting electrode 51 with a high reflectionefficiency is followed.

The reflecting electrode 51 has the uneven structure 50 reflectedthereon, so that a configuration of an uneven-element inclination angleon a surface of the reflecting electrode 51 determines an opticalproperty of a reflected light. Therefore, the inclination angle of theuneven structure 50 is designed so as to obtain a desired opticalproperty of reflection. To do so, the uneven structure 50 only has to beconfigured by two kinds or more of values in either of its protrusionpitch, depression pitch, protrusion height, and depression depth. Thereflecting electrode 51 is electrically connected via a contact hole 52formed in the insulator film 44 to a source electrode 53 of the TFT 40,thus functioning also as an electrode for pixels.

The following will describe operations of the reflection-type liquidcrystal display according to the first embodiment of the presentinvention.

When the liquid crystal layer 61 is in a white state, an incident light55 from outside the opposed-side substrate 1 passes through a polarizingplate 56, a phase-difference plate 57, the glass substrate 581, a colorfilter 59, the transparent electrode 60, and the liquid crystal layer 61and then is reflected according to a directivity which reflects theshape of an uneven surface 62 of the reflecting electrode 51 and againpasses through the liquid crystal layer 61, the transparent electrode60, the color filter 59, the glass substrate 581, the phase-differenceplate 57, and the polarizing plate 56, thus returning back to theoutside as a display light 63. When the liquid crystal layer 61 is in ablack state, on an other hand, the incident light 55 from outside theopposed-side substrate 1 is reflected by the reflecting electrode 51 ina same way as in a case of the white state but then blocked by thepolarizing plate 56, so that it is not emitted to the outside. Withthis, the display light 63 can be turned ON/OFF.

The following will describe variants of the reflection-type liquidcrystal display according to the first embodiment of the presentinvention.

The reflecting electrode 51 can be provided at a top of a pixel byforming the contact hole 52 in at least one of the first insulatinglayer 45 and second insulating layer 49 for electrically interconnectingoverlying reflecting electrode 51 and underlying TFT 40. Therefore, byincreasing area of the reflecting electrode 51, a higher numericalaperture can be achieved, hence brighter display can be realized.

Also, the protrusions 47 may be made of an organic or inorganic materialhaving photosensitivity. With this, a patterning step for forming theprotrusions 47 can be shortened. Specifically, formation of theprotrusions 47 is completed during steps of forming, exposing, andetch-developing a photosensitive resin, so that steps for resistapplying, film etching, and resist removing can be omitted in contrastto a case where prior art resist processes are employed.

Further, the second insulating layer 49 may be made of an organic orinorganic material having photosensitivity. With this, patterning stepsfor forming a contact pattern also can be shortened as compared to theprior art resist process, thus simplifying processes required. Thephotosensitive resin may come in products named “OFPR800” made by TokyoApplied Chemistry Industry Co., Ltd., “PC339” by Japan Synthetic RubberCo., Ltd., and other acrylic resins. The photosensitive insulatingmaterial also is not limited to the ones but may be other appropriateorganic or inorganic resins.

The following will describe one pixel of the first insulating layer 45in the reflection-type liquid crystal display according to the firstembodiment with reference to FIGS. 2A and 2B.

In a first mode shown in FIG. 2A, a large number of depressions 461isolated as surrounded by the protrusions 471 are arranged irregularly.The depressions 461 are recessed in a square. In a second mode shown inFIG. 2B, a large number of depressions 462 isolated as surrounded byprotrusions 472 are arranged irregularly. In this case, the depressions462 are corresponding to portions surrounded by a large number of thestripe-shaped protrusions 472 arranged irregularly. In the firstembodiment, the protrusions 471 and 472 can have a large area in contactwith the underlying layer, to thereby improve adherence therewith, thusproviding good protrusions that cannot easily flake off.

Second Embodiment

The following will describe a reflection-type liquid crystal, displayaccording to a second embodiment of the present invention with referenceto FIGS. 3A and 3B.

An uneven-element pattern according to the second embodiment only has tobe irregular over a region of one pixel or more in the reflection-typeliquid crystal display, for example, over a region in units of three orfour pixels of an RGB or RGGB type. Further, an irregular uneven-elementpattern 65 may be given in a region composed of five pixels or more andrepeated, to constitute uneven elements in a reflecting plate regiondisposed throughout on a panel display portion. In this case, it ispossible to obtain almost a same bright reflecting plate as in a casewhere a whole surface of the reflecting plate panel is formed ofirregular patterns.

FIG. 3A shows a first mode where an irregular arrangement pattern isrepeated in units of one pixel in the whole surface of a display region.FIG. 3B shows a second mode where an irregular pattern is repeated inunits of two pixels or more in the whole surface of the display region.A case of FIG. 3B is preferable because the irregular arrangementpattern can be repeated effectively. Although the second embodiment hasbeen performed with an isolated depression pattern, possible patternsare not limited to it. For example, the stripe-shaped pattern mentionedin the first embodiment, or a like may be used to obtain almost sameeffects.

Third Embodiment

The following will describe a reflection-type liquid crystal displayaccording to a third embodiment of the present invention with referenceto FIG. 4A.

In the third embodiment, heat treatment is conducted after protrusionsare formed, to thereby change an uneven shape, thus providing aplurality of smooth protrusion 66. With this, the uneven shape formed ona surface of a reflecting electrode 51 can be made smoother, thus givingbetter optical reflecting properties. Note here that a possible methodfor forming smooth and continuous protrusions is not limited to heattreatment described in the third embodiment but, for example, the smoothprotrusions 66 may be dipped in a solution having melting or swellingproperties to their material.

Fourth Embodiment

The following will describe a reflection-type liquid crystal displayaccording to a fourth embodiment of the present invention with referenceto FIG. 4B.

The first insulating layer 45 and the second insulating layer 49 areformed in such a way as to cover a TFT 40, a wiring line 67, a sourceelectrode 53, a drain electrode 54, or a like A reflecting electrode 51,which is electrically connected via a contact hole 52 to the TFT 40, hasan inter-layer separation structure by means of the second insulatinglayer 49. The first insulating layer 45 and second insulating layer 49both have a function as a protection film. The first insulating layer 45and second insulating layer 49 also are in direct contact with the TFT40, thereby being used as a passivation film for the TFT 40. Note herethat between the first insulating layer 45 and second insulating layer49 and the TFT 40 may be inserted a silicon nitride (SiN) or siliconoxide (SiO) film, which has been widely used as the passivation film forthe TFT.

Fifth Embodiment

The following will describe a reflection-type liquid crystal displayaccording to a fifth embodiment of the present invention with referenceto FIG. 5A through FIG. 5C.

In a prior art structure in FIG. 5A, a spacing between the reflectingelectrode 51 and a wiring line 67 is small, thus generating a largeparasitic capacitance therebetween. In a case of the fifth embodimentshown in FIG. 5B, on an other hand, at least one of a first insulatinglayer 45 and a second insulating layer 49 is arranged so as to cover thewiring line 67 (at least one of a drain and gate wiring lines). That is,the first insulating layer 45 and/or second insulating layer 49 can beused as an insulator film interposed between the reflecting electrode 51and the wiring line 67, so that this insulator film can be formed to athickness of 1-5 μm. With this, it is possible to reduce parasiticcapacitance occurring between the reflecting electrode 51 and the wiringline 67, thus suppressing occurrence of cross-talk or a like of thereflection-type liquid crystal display.

Further, as shown in FIG. 5C, the wiring line 67 and the reflectingelectrode 51 can be made to overlap each other, to thereby increase areaof the reflecting electrode 51 per pixel, thus realizing brighterdisplay performance. Note here that the first insulating layer 45 andsecond insulating layer 49 do not always have to be arranged on the gateor drain wiring line but, for example, they may be arranged on a TFT orits electrode.

Sixth Embodiment

The following will describe a reflection-type liquid crystal displayaccording to a sixth embodiment of the present invention with referenceto FIG. 6.

A second insulating layer 81 may be made of an organic or inorganicresin as far as it has insulating performance and also may havetransparency, coloring, and photo-absorbancy. The second insulatinglayer 81, particularly if it has photo-absorbancy, can completely absorba light 80 coming through a region where there is not a reflectingelectrode 51 present. With this, an incident light upon a TFT 40 can beshut out, to thereby prevent light-OFF leakage of properties of the TFT40, thus realizing a reflection-type liquid crystal display having goodswitching properties.

In such a case, the second insulating layer 81 having photo-absorbancymight well be used as an insulator film which provides an unevenstructure and, in order to obtain almost same effects, it only has to bearranged so as to prevent a light from being applied upon the TFT 40, sothat its arrangement is not limited to a position shown in FIG. 6.

In this case, however, if a photo-absorbing layer havingphotosensitivity is used as a smooth uneven film formed under thereflecting electrode 51, processes can be simplified. By using, as itsmaterial, products named “Black Resist,” “CFPR,” “BK-748S, ” “BK-430S,”or a like, it is possible to form a good photo-absorbing layer and agood uneven structure. Also, other appropriate black resin materials maybe used to obtain almost same effects. As the photo-absorbing layer,also, a photo-absorbing or photo-reflecting film or further a metalmaterial or a non-light-transmitting insulating material or inorganiccompound film may be used.

Seventh Embodiment

The following will describe a method for manufacturing a reflection-typeliquid crystal display according to a seventh embodiment of theinvention with reference to FIGS. 7 and 8.

These two figures show steps for manufacturing a substrate side of aswitching element. Note here that in the seventh embodiment, a reversestagger-structured TFT is used as the switching element.

The method for manufacturing a TFT substrate according to the seventhembodiment includes steps of:

forming, as step A, an electrode material (FIG. 7AB);

forming, as step B, a gate electrode 90 (FIG. 7AB);

forming, as step C, a gate insulator film 9l, a semiconductor layer 92,and a doping layer 93 (FIG. 7C);

forming, as step D, an island 94 (FIG. 7D);

forming, as step E, an electrode material (FIG. 7EF);

forming, as step F, a source electrode 95 and a drain electrode 96 (FIG.7EF);

forming, as step G, a first insulating layer 97 (FIG. 7G);

forming, as step H, a protrusion 98 (FIG. 8H);

transforming, as processing step I, a surface shape (FIG. 8I);

forming, as step J, a second insulating layer 99 (FIG. 8JK);

forming, as step K, a contact hole 100 (FIG. 8JK); and

forming, as step L, a reflecting electrode 101 (FIG. 8L).

Moreover, the step H includes processes on the first insulating layer 97of:

(1) forming a resist;

(2) forming a resist pattern for forming uneven elements;

(3) forming a protrusion 98; and

(4) removing the resist.

In this case, the step of the protrusion 98 can be controlled by filmthickness of the first insulating layer 97 during the step G. Therefore,a depression-protrusion portion (step) only has to be determined on abasis of a height necessary for desired optical properties of areflecting plate, specifically in an a range of 0.4-5.0 m in order toobtain good photo-reflecting properties.

In a surface-shape transforming processing of the step I, a surface ofthe protrusion 98 after pattern formation is melted by heat treatment at150-300° C. to be transformed into a smooth shape. Note here thatbesides heat treatment, this surface-shape transforming processing mayemploy any other processing, for example, melting processing by use ofchemicals.

Also, although as the reflecting electrode 101 has been used an Almaterial, which is a high-efficiency metal, a silver metal or a silveralloy may be used to obtain a higher reflection efficiency, thusrealizing brighter reflection performance. Also, as a switching element,a forward stagger-structured TFT, a MIM diode or a like may be used. Thereverse stagger-structured TFT also is not limited to a structureemployed in the seventh embodiment but may be of any other appropriatestructure.

Also, although a lower side substrate having the switching element andan opposed-side substrate have been made of glass, these substrates maybe made of any other appropriate materials, for example, plastic,ceramic, semiconductor, or a like

Eighth Embodiment

The following will describe a method for manufacturing a reflection-typeliquid crystal display according to an eighth embodiment of the presentinvention.

The eighth embodiment is same as the first embodiment shown in FIG. 7ABthrough FIG. 8L except that a first insulating layer and a secondinsulating layer are made of photosensitive materials.

The eighth embodiment employs a photosensitive resin as a material of afirst insulating layer 97 to thereby enable processing of patterns, information of protrusions 98, by direct exposure and development of thephotosensitive resin, thus simplifying steps of applying and removingresists. Further, the eighth embodiment employs a photosensitive resinas a material of the second insulating layer 99 also to similarlysimplify the pattern forming steps in formation of the contact hole 100.Therefore, the eighth embodiment can largely shorten manufacturing stepsas compared to those of the first embodiment shown in FIG. 7AB throughFIG. 8L, thus resulting in lower costs of the reflection-type liquidcrystal display.

FIRST EXAMPLE

The following will describe a reflection-type liquid crystal displayaccording to a first example of the present invention with reference toFIG. 9AB through FIG. 10LM.

The first example employs a forward stagger-structured TFT as aswitching element. A method for manufacturing the reflection-type liquidcrystal display according to the first example includes steps of:

forming, as step A, Cr layer to a thickness of 50 nm on a glasssubstrate by sputtering (FIG. 9AB);

forming, as step B, a source electrode 200 and a drain electrode 201 (bymeans of a photographic process) (FIG. 9AB);

forming, as step C, a doping layer 202 to a thickness of 100 nm, asemiconductor layer 203 to a thickness of 100 nm, and a semiconductorfilm 204 to a thickness of 50 nm by use of plasma CVD (Chemical VaporDeposition) respectively (FIG. 9C);

forming, as step D, an island (by means of a photographic process) (FIG.9DE);

forming, as step E, a gate insulator film 204 to a thickness of 350 nmby plasma CVD (FIG. 9DE);

forming, as step F, a Cr layer a thickness of 50 nm by sputtering (FIG.9FG);

forming, as step G, a gate electrode 207 (FIG. 9FG);

forming, as step H, a first organic insulator film 208 to a thickness of3 μm (FIG. 9H);

forming, as step I, a pattern of a protrusion 209 (by means of aphotographic process) (FIG. 10);

forming, as step J, a second organic insulator film 210 to a thicknessof 1 μm (FIG. 10JK);

forming, as step K, a contact hole 211 (by means of a photographicprocess) (FIG. 10JK);

forming, as step L, an aluminum layer to a thickness of 300 nm bysputtering (FIG. 10LM); and

forming, as step M, a reflecting pixel (picture element) electrodeplate, reflecting electrode 212 (by means of a photographic process)(FIG. 10LM).

In the step C, the first example uses a silicon nitride film as the gateinsulator film 204, an amorphous silicon film as the semiconductor layer203, and an N-type amorphous silicon film as the doping layer 202.Conditions for the above-mentioned plasma CVD method are set as follows.For the silicon oxide film, silane and an oxygen gas are used as areactive gas, gas flow ratio (silane/oxygen) is about 0.1-0.5, the filmforming temperature is 200-300° C., the pressure is 133 Pa, and plasmapower is 200 W. For the silicon nitride film, silane and an ammonium gasare used as a reactive gas, gas flow ratio (silane/ammonium) is 0.1-0.8,the film forming temperature is 250° C., pressure is 133 Pa, and plasmapower is 200 W. For the amorphous silicon film, silane and a hydrogengas are used as a reactive gas, the gas flow ratio (silane/hydrogen) is0.25-2.0, the film forming temperature is 200-250° C., pressure is 133Pa, and plasma power is 50 W. For the N-type amorphous silicon film,silane and phosphine were used as the reactive gas, the gas flow ratio(silane/phosphine) is 1-2, the film forming temperature is 200-250° C.,the pressure is 133 Pa, and the plasma power is 50 W.

Also, in the step D of forming the island, dry etching is conducted onthe silicon nitride film and the amorphous silicon layer. In the step Gof forming the gate electrode 207, the Cr layer is etched using amixture solution of perchloric hydracid and secondary cesium-ammoniumnitrate. Also, the silicon nitrate film is etched using fluorinetetrachloride and an oxygen gas as the etching gas at a reactivepressure of 0.665-39.9 Pa and a plasma power of 100-300 W. Also, theamorphous silicon layer is etched using chloride and a hydrogen gas asan etching gas at a reactive pressure of 0.665-39.9 Pa and at a plasmapower of 50-200 W. Also, in every photolithography step, an ordinaryresist process is employed.

Although the first example uses Cr as the source and drain electrodesand Cr metal as the gate electrode, possible electrode materials are notlimited to these. Besides them, single-layer films made of Ti, W, Mo,Ta, Cu, Al, Ag, ITO (Indium Tin Oxide), ZnO, SnO, or a like or astacked-layer film made of a combination thereof may be employed as theelectrode materials.

In the first example, the uneven elements provided at the lower part ofthe reflecting plate are formed in the steps I and J. The following willdescribe a method for forming the uneven elements.

On the first organic insulator film 208 formed in the step H, a resistfilm is formed to a thickness of 2 μm, to subsequently perform exposureand development processes to form a resist pattern in which continuousstripe-shaped patterns are arranged irregularly. Then, the organicinsulator film 208 is etched to remove the resist, thus forming theprotrusion 209. FIG. 11 shows a panel display region pattern and itsexpanded figure. In FIG. 11, a continuous stripe-shaped protrusion 215and, an isolated depression 216 are shown.

The first example employs a polyimide film (product by Nissan ChemicalIndustry Co., Ltd. named “RN-812”) as the first organic insulator film208 processed in the step H. Application is conducted under conditionsof a spin speed of 1200 rpm, a temporary baking temperature of 90° C., atemporary baking time of 10 minutes, a main baking temperature of 250°C., and a main baking time of one hour. In the case of the resist, theconditions are a spin number of revolutions of 1000 rpm, a temporarybaking temperature of 90° C., a temporary baking time of five minutes,and a post-baking temperature of 90° C. for a processing time of 30minutes after the pattern is formed by the subsequent exposure anddevelopment. The conditions for dry etching on the polyimide filmperformed using the resist as a mask layer are use of fluorinetetrachloride and an oxygen gas, a gas flow ratio (fluorinetetrachloride/oxygen) of 0.5-1.5, a reactive pressure of 0.665-39.9 Pa,and a plasma power of 100-300 W. Note here that in everyphotolithography step, an ordinary resist process is employed.

In the step K of forming the contact hole 211, a resist process is toform the pattern. In this case, in order to form the contact hole 211,both a polyimide film which provides the second organic insulator film210 and a silicon nitride film which provides the gate insulator film204 are etched using a dry etching process.

Also, although a same organic resin material is used as the firstorganic insulator film 208 and the second organic insulator film 210,other materials may be used to form almost same uneven insulator films.The first organic insulator film 208 and second organic insulator film210 can be realized by a combination of an inorganic resin and anorganic resin or a reverse combination thereof such as an acrylic resinand a polyimide resin, a silicon nitride film and an acrylic resin, or asilicon oxide film and a polyimide resin.

Then, in the first example, an aluminum metal layer having a highreflection efficiency and fits well to the TFT process is formed andpatterned into the reflecting electrode 212 as a pixelelectrode-and-reflecting plate. In this case, the aluminum metal issubjected to wet etching in an etchant mixture solution of a phosphoricacid, an acetic acid, and a nitric acid heated to 60° C.

Here, a maximum depression-protrusion portion (step) on the surface ofthe reflecting electrode 212 is about 1 μm with the uneven-elementsurface shape being random. Then, the TFT substrate and the opposingsubstrate having a transparent electrode formed of ITO of thetransparent conductive film are superposed one on the other with theirrespective film surfaces facing each other. In this case, the TFTsubstrate and the opposing substrate are oriented and bonded to eachother with a spacer made of plastic particulate or a like therebetweenby applying an epoxy-based adhesive agent at peripheries of the panel.Then, liquid crystal is injected to provide a liquid crystal layer, thusmanufacturing the reflection-type liquid crystal display.

The reflecting electrode 212 is free of flake-off of the protrusions 209and so is uniform and reflective having good light scatteringperformance. With this, the reflection-type liquid crystal displayemploying the reflecting electrode 212 has display performance goodenough to realize a monochromatic reflection-type panel having whitedisplay brighter than a newspaper. Also, an RGB color filter isinstalled on the side of the opposing substrate to realize a brightmulti-color reflection-type panel.

Note here that a peak-bottom difference at a step between the depressionand the protrusion in the first example (height of the protrusion 209)is not limited to the above-mentioned value. This peak-bottom differenceis variable in a wide range, so that an uneven structure according tothe invention can be employed to provide a reflection-type liquidcrystal display having largely changed directivity of reflectionperformance.

Although the first example employ a stripe-shaped pattern as the patternformed in the first organic insulator film 208, a possible pattern isnot limited thereto. An isolated depression pattern shown in FIG. 12 mayalso be used to realize a reflection-type liquid crystal display havingalmost same display performance.

SECOND EXAMPLE

The following will describe a reflection-type liquid crystal displayaccording to a second example of the present invention with reference toFIG. 13AB through FIG. 14KL. The second example employs a reversestagger-structured TFT as a switching element.

A method for manufacturing the reflection-type liquid crystal displayaccording to the second example includes the steps of:

forming, as step A, a Cr layer to a thickness of 50 nm on a glasssubstrate 230 by sputtering (FIG. 13AB);

forming, step B, a gate electrode 231 (by means of a photographicprocess) (FIG. 13AB);

forming, as step C, a gate insulator film 232 to a thickness of 400 nm,a semiconductor layer 233 to a thickness of 100 nm, and a doping layer234 to a thickness of 100 nm by plasma CVD respectively (FIG. 13C);

forming, as step D, an island 235 (by means of a photographic process)(FIG. 13D);

forming, as step E, Cr and ITO layers to a thickness of 50 nmrespectively by sputtering (FIG. 13EF);

forming, as step F, a source electrode 236 and a drain electrode 237 (bymeans of a photographic process) (FIG. 13EF);

forming, as step G, a first organic insulator film 238 to a thickness of3 μm (FIG. 13G);

forming, as step H, a protrusion 239 (by means of a photographicprocess) (FIG. 14H);

forming, as step I, a second organic insulator film 240 to a thicknessof 1 μm (FIG. 141J);

forming, as step J, a contact hole 241 (by means of a photographicprocess) (FIG. 141J);

forming, as step K, an aluminum layer to a thickness of 300 nm bysputtering (FIG. 14KL);

forming, as step L, a reflecting electrode 243 (by means of aphotographic process) (FIG. 14KL); and

terminating, as step M, a gate wiring line (by means of a photographicprocess).

The protrusion 239 in the second example is formed during the step H.For this step, same conditions are employed as those for the firstexample. In the second example, a reverse stagger-structured transistoris employed, so that number of steps required is increased as comparedto the first example.

In the second example, the reflecting electrode 243 is manufactured withits numerical aperture of 86%. Then, the TFT substrate and opposingsubstrate having a transparent electrode formed of ITO of a transparentconductive film are superposed one on an other so that their respectivefilm surfaces face each other. Specifically, those TFT substrate andopposing substrate are oriented respectively and bonded to each otherwith a spacer made of plastic particulate or a like therebetween byapplying an epoxy-based adhesive agent to peripheries of a panel. Then,liquid crystal is injected to manufacture the reflection-type liquidcrystal display.

Like in a case of the first example, the reflection-type liquid crystaldisplay according to the second example exhibited avoids process damageson a switching element to thereby obtain good element properties as wellas a desired uneven reflecting-plate structure. As a result, amulti-color reflection-type panel manufactured according to the secondexample exhibits bright and high-definition display.

THIRD EXAMPLE

The following will describe a reflection-type liquid crystal displayaccording to a third example of the present invention with reference toFIG. 15AB and FIG. 16L.

The first example features that a protrusion disposed under a reflectingelectrode is formed in a smooth uneven shape. A manufacturing methodaccording to the third example is same as that according to the first orthe second example except that a process is added for transforming anuneven element disposed under the reflecting electrode into a smoothshape. That is, a heat treatment step is added following format-on of anuneven-element pattern in a step I of the first example or a step H ofthe second example.

The third example performs heat treatment after formation of a unevenstructure in a nitrogen atmosphere in an oven set at 260° C. for onehour. With this, a inclination angle of the uneven structure changesfrom a pre-heat treatment angle of about. 60-80 degrees to a post-heattreatment angle of about 10-40 degrees. Thus obtained uneven shape istransformed from a rectangular shape into a sine-curved smoothprotrusion 250. In the reflection-type liquid crystal display accordingto the third example, an average of the uneven-element inclination angleon the uneven surface is set at about eight degrees. The uneven-elementinclination angle can be controlled by changing baking temperature inthe heat treatment.

Also, a top-bottom difference of the uneven structure finally formed ona surface of the reflecting electrode is set at 1 μm like in cases ofthe first and the second examples. If this uneven-structure top-bottomdifference is increased further, resultant optical properties of thereflecting electrode exhibit a very strong light-scattering performance.This scheme can be applied to a reflection-type liquid crystal displayhaving a particularly large-sized screen to thereby reduce view-fielddependency of panel display brightness, thus obtaining easy-to-seedisplay. If this uneven-structure top-bottom difference is decreased, onthe other hand, optical properties of the reflecting electrode exhibitstrong directivity. This scheme can be applied to a reflection-typeliquid crystal display for use in portable information equipment havinga relatively small-sized screen, thus obtaining brighter display. Insuch a manner, the uneven surface structure can be arbitrarilycontrolled according to applications or panel display area.

In the third example, an insulator film is disposed between an overlyingreflecting electrode and an underlying switching element, thusfunctioning as a protection film for that switching element.

FOURTH EXAMPLE

The fourth example features that an organic insulator film havingphotosensitivity is used as an insulating layer disposed under anreflecting electrode. Processes for manufacturing a reflection-typeliquid crystal display according to the fourth example are same as thoseaccording to the first or second example except that a photosensitiveresin (photosensitive acrylic resin in the fourth example) is used-asthe insulating layer under the reflecting electrode. That is, the fourthexample differs from them in that a photosensitive film is used as theinsulating layer which is formed in steps H and I of the first exampleor steps G and I of the second example.

Only by adding a step of forming a photosensitive film, anuneven-element forming step is changed to a step of forming aphotosensitive film, a step of direct exposure of a photosensitive film,a step of etch-development, and a step of melting by use of heattreatment. With this, in contrast to the uneven-element forming processperformed in the first, the second, and the third examples, the fourthexample can eliminate a need of resist application, development, andremoval steps, thus simplifying processes.

Although the fourth example has used a photosensitive acrylic resin as aphotosensitive material, possible photo-sensitive materials are notlimited to it. Other appropriate photosensitive materials, for example,a photosensitive organic resin, a photosensitive inorganic film, or alike can realize same effects. Note here that such photosensitivematerials as products named “OFPR800” by Tokyo Applied ChemistryIndustry Co., Ltd., “LC100” by Shipley Corporation, “Optomer Series” byJapan Synthetic Rubber Co., Ltd., “Photosensitive Polyimide” by NissanChemistry Industry Co., Ltd. or a like can be used to obtain almost asame uneven insulating layer.

FIFTH EXAMPLE

The fifth example employs a reverse stagger-structured TFT as aswitching element. Basic manufacturing processes according to the fifthexample are same as those shown in FIG. 15AB and FIG. 16L except that aphotosensitive resin is used as a first insulating layer and a secondinsulating layer and that a resist process is omitted in forming aprotrusion and a contact hole. A method for manufacturing areflection-type liquid crystal display according to the fifth exampleincludes steps of:

forming, as step A, a Cr layer (not shown) to a thickness of 50 nm onthe glass substrate 230 by sputtering (FIG. 15AB);

forming, as step B, a gate electrode 231 (by means of a photographicprocess) (FIG. 15AB);

forming, as step C, a gate insulator film 232 to a thickness of 400 nm,a semiconductor layer 233 to a thickness of 100 nm, and a doping layer234 to a thickness of 100 nm by plasma CVD respectively (FIG. 15 C);

forming, as step D, an island 235 (by means of a photographic process)(FIG. 15D);

forming, as step E, Cr and ITO layers (not shown) by sputtering to athickness of 50 nm respectively (FIG. 15EF);

forming, as step F, a source electrode 236, a drain electrode 237, andan uneven-element forming electrode (by means of a photographic process)(FIG. 15EF);

forming, as step G, a photosensitive acrylic resin layer to a thicknessof 3 μm (FIG. 15G);

exposing, as step H, all uneven-element pattern onto the photosensitiveacrylic resin (by means of a photographic process) (FIG. 16H);

forming, as step I, uneven elements by use of development-etching step(FIG. 16I);

exposing, as step J, a contact pattern onto the photo-sensitive acrylicresin (by means of a photographic process) (FIG. 16JK);

forming, as step K, a contact hole 241 by use of a development-etchingstep (FIG. 16JK);

forming, as step L, an aluminum layer to a thickness of 300 nm bysputtering (FIG. 16L);

forming, as step M, a reflection pixel electrode plate (by means of aphotographic process); and

terminating, as step N, a gate wiring line.

Afterward, opposing substrates are superposed one on an other tomanufacture the reflection-type liquid crystal display. A thus obtainedreflection-type liquid crystal display can realize bright andhigh-definition multi-color display.

FIG. 17 shows a pattern used to form the protrusion 239 in the step H.As shown in it, a continuous stripe-shaped pattern is used to patternthe first and second insulating layers so as to cover a gate wiring lineand a drain wiring line. With this, parasitic capacitance is reducewhich occurs between a reflecting electrode and a wiring line, to obtaingood panel display performance. Also, when an isolated depressionpattern shown in FIG. 18 is used, the reflection-type liquid crystaldisplay having almost same display performance is obtained. Note herethat in FIGS. 17 and 18, a continuous striped-shaped protrusion 215, anisolated depression 216, a stripe-shaped protrusion 260 on the wiringline, a stripe-shaped protrusion 261 on the gate wiring line, and astripe-shaped protrusion 262 on the drain wiring line are shown.

In all the figures, same elements are indicated by same referencenumerals, thus omitting duplicated description.

By the reflection-type liquid crystal display and method formanufacturing same according to the invention, all the protrusions 239on the insulator film under the reflecting electrode are connected in anetwork, so that if some of all of these protrusions 239 have weakeradherence with the underlying layer, they can be supported bysurrounding protrusions, thus preventing flake-off of the protrusions239 as a whole.

In other words, since protrusions 239 formed on the first insulatinglayer are constituted by a plane pattern composed of isolateddepressions or a continuous stripe, the protrusions 239 can have a largearea in contact with the underlying layer, thus improving theiradherence with the underlying film. This leads to realization of goodprotrusions free of film flake-off. Also, the reflection-type liquidcrystal display employing the reflecting electrode formed on thoseprotrusions can provide uniform and high-definition display havingdesired optical reflection properties.

It is apparent that the present invention is not limited to the aboveembodiments but may be changed and modified without departing from thescope and spirit of the invention.

1. A method for forming an insulator film for manufacturing areflection-type liquid crystal display, the insulator film comprisingfirst and second insulating layers, the method comprising: forming anuneven-element pattern in the first insulating layer, saiduneven-element pattern comprising a plurality of stripe-shapedprotrusions connected in a network; forming said second insulating layerof an organic or inorganic insulating material having photosensitivity;forming a pattern used to form a contact hole in said second insulatinglayer; and performing etch-developing on said second insulating layer,to thereby form said contact hole.
 2. The method according to claim 1,further comprising a large number of depressions in said firstinsulating layer isolated by the interconnected protrusions.
 3. Themethod according to claim 1, wherein said second insulating layer isformed on said first insulating layer and wherein the first and secondinsulating layers are of different thickness.
 4. The method according toclaim 1, wherein said second insulating layer is a separate layer thatentirely covers the first insulating layer.
 5. A method formanufacturing a reflection-type liquid crystal display, the methodcomprising: providing a transparent electrode on a transparent firstsubstrate; providing an insulator film on a second substrate; providingon a surface of the insulator film an uneven structure and a reflectingelectrode in such a shape as reflecting said uneven structure;sandwiching a liquid crystal layer by a side of said transparentelectrode formed on said first substrate and a side of said reflectingelectrode provided on said second substrate; providing a liquid crystaldriving switching element on said second substrate; forming anuneven-element pattern in a first insulating layer of the insulatorfilm, said uneven-element pattern comprising a plurality ofstripe-shaped protrusions connected in a network; forming a secondinsulating layer of an organic or inorganic insulating material havingphotosensitivity, wherein the insulator film further comprises thesecond insulating layer and wherein a second insulating layer is aseparate layer which covers said first insulating layer entirely;forming a pattern used to form a contact hole in said second insulatinglayer; and performing etch-developing on said second insulating layer,to thereby form said contact hole, wherein the contact hole in saidinsulator film electrically interconnects the liquid crystal drivingswitching element and the reflecting electrode.
 6. The method accordingto claim 5, further comprising a large number of depressions in saidfirst insulating layer isolated by the interconnected protrusions. 7.The method according to claim 5, wherein said second insulating layer isformed on said first insulating layer and wherein the first and secondinsulating layers are of different thickness.
 8. The method according toclaim 5, wherein said second insulating layer is a separate layer thatentirely covers the first insulating layer.
 9. The method according toclaim 1, wherein said plurality of said stripe-shaped protrusions arearranged irregularly.
 10. The method according to claim 5, wherein saidplurality of said stripe-shaped protrusions are arranged irregularly.